This invention relates to a dubbing apparatus by which information in the form of an audio signal recorded, for example, on a disk-type recording medium can be reproduced and recorded onto another recording medium.
In recent years, disk media onto and from which audio data can be recorded and reproduced such as, for example, a mini disk (MD, trademark) and recording and reproduction apparatus on which such disk media can be used have been popularized widely.
Also an audio system which includes a combination of, for example, a MD recorder/player which is a recording and reproduction apparatus for a MD and a CD player or the like has been popularized widely.
In such a system as a MD recorder/player and a CD player or the like as described above, audio data are managed in a unit called xe2x80x9cprogramxe2x80x9d. Here, a program in the present specification signifies a set of data which are managed and recorded in a unit on a disk, and for example, with regard to audio data, it corresponds to one tune (generally called xe2x80x9ctrackxe2x80x9d) or the like. Therefore, in the following description, a program may suitably referred to as track.
Such an audio system as described above is usually constructed such that it can effect dubbing recording, that is, recording of audio data reproduced by the CD player onto a MD by the MD recorder/player.
Also a system is available which can effect high speed dubbing to reduce the recording time in such dubbing recording.
Upon high speed dubbing, a disk rotational driving control system and a reproduction signal processing system of the CD player are controlled so that a CD may be played back at a predetermined multiple speed higher than a normal reproduction speed. Also on the MD recorder/player side, a recording signal processing system is controlled so as to operate at a multiple speed corresponding to the reproduction multiple speed for a CD, and receives audio data reproduced by the CD player and records the audio data onto a MD.
For example, in an apparatus wherein a CD player as a reproduction apparatus and a MD recorder/player as a recording apparatus are integrated with each other, it is easy to control the CD player and the MD recorder/player so that they may simultaneously operate at a predetermined multiple speed so as to perform such high speed dubbing as described above. Also in another system wherein a reproduction apparatus and a recording apparatus are formed as separate units from each other, if the system is constructed such that, for example, a controlling cable or the like is used to connect the reproduction apparatus and the recording apparatus to each other so as to allow communication with each other, then high speed dubbing can be realized readily by controlling operations of the reproduction apparatus and the recording apparatus in synchronism with each other.
In a reproduction apparatus for a CD, a disk is driven to rotate in accordance with a CLV (Constant Linear Velocity) method as well known in the prior art, and an EFM signal reproduced from the CD is supplied to a PLL circuit. The PLL circuit is provided in order to produce a channel clock signal synchronized with the EFM signal. When the PLL circuit is in a locked state, the CD is driven to rotate stably at a prescribed CLV speed and a reproduction signal is processed normally.
In such an audio system as described above, when a CD is played back with a multiple speed higher than a normal speed in order to perform high speed dubbing, the PLL circuit is less likely to enter a locked state than when a CD is played back with a normal speed.
It is considered that this arises from the fact that, for example, when a disk is rotated at a high speed, the disk whirls in a shorter period with regard to a radial direction of the disk which is caused by eccentricity of the disk, and this deteriorates the follow-up performance of tracking servo control. Further, a CD is driven to rotate while it is fixedly held at a central position thereof by a chucking mechanism. However, when a CD is driven to rotate at a high speed, the holding force by the chucking mechanism does not sufficiently effectively work, resulting in slip of the CD. Consequently, the linear velocity of the CD as viewed from the optical head side varies. Also this is considered to be a cause of the phenomenon described above.
Further, a CD system involves error correction in which codes called CIRC are used. It is assumed here that high speed reproduction, for example, at a double speed is performed while a normal speed is used for a system clock signal for a signal processing system for playback of a CD. In this instance, the error correction processing of the CD system is limited from the arithmetic processing speed of the signal processing system such that, whereas double correction processing is performed for the C1 parity and quadruple correction processing is performed for the C2 parity upon normal speed reproduction as well known in the prior art, double correction processing is performed for the C1 parity and double correction processing is performed for the C2 parity upon double speed reproduction.
Consequently, the error correction ability is deteriorated more upon high speed reproduction than normal speed reproduction by a same disk defect such as a damage, a foreign article or the like to a CD. Also this deteriorates the stability of a reproduction operation.
A system which plays back, for example, a CD performs interpolation processing if a result that error correction according to the C2 parity is NG is obtained as well known in the prior art. However, since data obtained by the interpolation have values different from those of an actual audio signal waveform, depending upon a result of the interpolation or the duration of a period within which the interpolation is performed, the data may possibly sound as interpolation noise.
Accordingly, in high speed dubbing which involves high speed playback of a CD, since a reproduction operation of a CD is rendered unstable from such reasons as described above, also interpolation noise is liable to be generated. Therefore, for example, when sound recorded on a MD by high speed dubbing is reproduced, there is the possibility that such interpolation noise as described above may sound to such a degree that it cannot be ignored. In this manner, in high speed dubbing, since at least a reproduction operation of the reproduction (CD) side which performs multiple speed reproduction becomes unstable, there is the possibility that the quality (sound quality) of data recorded by dubbing cannot be secured.
A possible countermeasure against this is, for example, as a countermeasure based on a determination of a user, to perform high speed dubbing and, if significant interpolation noise is included in a result of the recording, perform recording by a normal speed dubbing operation. However, even if noise is included in recorded sound, normally it is difficult for an ordinary user to discriminate whether the noise is interpolation noise or noise originating from some other cause such as, for example, a fault of the recording side.
Another possible countermeasure is to adopt, upon high speed dubbing, a higher speed as the set speed of the system clock signal corresponding to the reproduction multiple speed in order to augment the error correction capacity described above. However, this gives rise to another problem that, since unnecessary radiation according to the system clock signal of the increased speed increases, an additional cost is required for a countermeasure against radiation noise.
It is an object of the present invention to provide a recording and reproduction apparatus, a reproduction apparatus, a recording and reproduction method and a reproduction method by which interpolation noise of reproduced information is reduced and a recording medium on which information of higher quality is recorded can be produced.
In order to attain the object described above, according to the present invention, there is provided a recording and reproduction apparatus which includes a reproduction section for reading out information recorded on a disk-type first recording medium, and a recording section for recording the information read out by the reproduction section onto a second recording medium, comprising rotational driving means for rotationally driving the first recording medium at a first rotational speed, reproduction head means for reading out the information recorded on the first recording medium rotationally driven by the rotational driving means, feeding means for feeding the reproduction head means in order to read out the information recorded at a designated position of the first recording medium, error detection means for detecting an error state of the information read out from the first recording medium by the reproduction head means, feeding control means for controlling the feeding means so that, when an error is detected by the error detection means, the reproduction head means may be fed to a reproduction position preceding to a reproduction position of the first recording medium at which the error is detected, and rotational driving control means for controlling the rotational driving means so that, after the reproduction head means is fed to the preceding reproduction position under the control of the feeding control means, the first recording medium rotationally driven by the rotational driving means may be rotated at a second rotational speed lower than the first rotational speed.
In the recording and reproduction apparatus, if it is detected that a reproduction error state of such a degree that it corresponds to occurrence of interpolation noise which occurs with a frequency higher than a predetermined frequency occurs while a disk-type first recording medium is rotationally driven at a first rotational driving speed higher than a second rotational driving speed which may be a normal speed in the reproduction section, then the reproduction head means accesses a reproduction position preceding to a reproduction position of the reproduction head means at which the error is detected, and then the first recording medium is rotated at the second rotational driving speed such as, for example, the normal speed, lower than the first rotational driving speed to start reproduction of the first recording medium beginning with the thus accessed preceding position. Thereafter, for example, when a next program (track) is to be reproduced, the first rotational driving speed is set again.
In the recording and reproduction apparatus, as steady dubbing operation, high speed dubbing operation which involves reproduction according to the first rotational driving speed is performed. But in a situation wherein it is determined based on a result of detection of an error that the reproduction operation is unstable, low speed dubbing operation which involves reproduction according to the second rotational driving speed is executed. Since the reproduction according to the second rotational driving speed stabilizes the reproduction operation, information obtained by the dubbing includes little errors. Where the recording and reproduction apparatus is applied, for example, to audio data, interpolation noise decreases as much, and consequently, a sound source recorded with good sound quality can be obtained.
Further, in the recording and reproduction apparatus, since there is no necessity, for example, to raise the rate of a system clock signal on the reproduction side to reinforce the error correction ability in order to make errors less likely to occur even if high speed dubbing (that is, high speed rotational driving on the reproduction side) is continued intentionally, the processing burden is reduced and increase in cost can be eliminated.
Preferably, the recording and reproduction apparatus is constructed such that the information recorded on the first recording medium is managed in a unit of a program, and the preceding reproduction position is a reproduction starting position of a program which is reproduced upon detection of an error by the error detection means. Thus, in the recording and reproduction apparatus, when the reproduction position preceding to the reproduction position at which the error occurs is to be accessed on the reproduction sides the recording head means returns to the starting position of the current program (track) which has been reproduced upon occurrence of the error. In other words, returning accessing is performed.
Consequently, as part of the dubbing operation, retrying of reproduction (according to the second rotational driving speed) is automatically performed from the beginning of the program with which the dubbing has failed because of occurrence of the error. As a result, the program reproduced appropriately can be recorded substantially with certainty onto the second recording medium on the recording side.
Preferably, the information is recorded in a unit of a program onto the second recording medium, and the position of the second recording medium corresponding to the preceding reproduction position is a recording starting position of a program which is recorded upon detection of an error by the error detection means. Thus, when such returning accessing as described above is performed on the reproduction side, returning accessing wherein the accessing position to the second recording medium is returned to a recording position preceding to a recording position at which the error has occurred is performed similarly on the recording side. Consequently, on the recording side, recorded data whose sound quality cannot be anticipated because of the error is erased at least by overwriting with data by later dubbing recording. Further, where the accessing position is returned to the recording position corresponding to the reproduction position preceding to the reproduction position at which the error has occurred on the reproduction side, data whose contents are continuous before and after the occurrence of the error can be recorded onto the second recording medium.
Further, since, upon the returning accessing on the recording section side, the accessing position is returned to the recording starting position of the current program (track) for which recording has been proceeding upon the occurrence of the error, data of the program whose dubbing has failed due to the occurrence of the error is erased by overwriting by recording of information of the program reproduced later according to the first rotational driving speed.
Consequently, data of a program whose dubbing has failed due to occurrence of an error during dubbing operation does not remain on the second recording medium. Therefore, for example, it is not necessary for a user to erase a track, whose dubbing has failed, later. Further, since the recording remaining time of the second recording medium on the recording side is not reduced by data of a program which otherwise remains due to failure in dubbing, the recordable time of the second recording medium can be made most of to perform dubbing.
The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements denoted by like reference symbols.